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Post by Philconut on Aug 6, 2021 22:34:44 GMT 12
I'm very interested in the re-silvering you did on the clock face. As a result of the paint issues, I have removed the nickel plating on all the raised parts of the panel. My electroplater expressed doubts about being able to re-plate it successfully so I settled with the brass which will look fine. If I could somehow rework the plating that would be a bonus. One of our local VR group is an expert spray painter and he has offered to redo the paintwork for me. - we discussed it at length at last night's meeting. Seems it is much more involved than I ever imagined so I look forward to learning something. I have had a new leather carry handle made and am part way through restoring the case so still some progress. The electronics are ready to test when it is all back together.
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peter
Tinkerer
Retired, collector of vintage radios and test equipment for restoration and repair.
Posts: 97
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Post by peter on Aug 9, 2021 3:42:31 GMT 12
Can I ask you people as Valve tester repair enthusiasts what your general opinion is on replacing the wooden box these things are often mounted in. I have one (forget the model) but the point is the box is little more than woodworm holding hands. I think it might be easier to make a replica box than to kill off all the active worm in it.
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Post by DHockey on Aug 9, 2021 7:49:48 GMT 12
Silvering brass is done with silver chloride. You mix the silver chloride into a paste with a little water and rub it over the clean brass with a damp cloth. It reacts with the brass and gives a silver colour to it. After the silver chloride has been applied, cream of tartar is rubbed over the brass in the same manner to give a uniform finish. To prevent rapid tarnishing the finished brass is usually sealed with lacquer or wax. There is a good “how to do it” tutorial here: www.davewestclocks.co.uk/silvering_clock_dials.htm I agree, spray painting is an art in itself. With something like a the front panel of a piece of test equipment, having an expert do it is worthwhile.
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Post by DHockey on Aug 9, 2021 7:50:50 GMT 12
Hi Peter
If the case of your tester is completely infested, replacing it / rebuilding it would be the best option in my opinion. After a certain point the wood loses its strength and the risk of further infestation remains as borer treatments wear off over years due to UV light exposure etc.
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Post by Philconut on Aug 9, 2021 8:51:44 GMT 12
Thanks for the link to the excellent article. I will pursue that this week.
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peter
Tinkerer
Retired, collector of vintage radios and test equipment for restoration and repair.
Posts: 97
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Post by peter on Aug 9, 2021 23:42:59 GMT 12
Hi Peter If the case of your tester is completely infested, replacing it / rebuilding it would be the best option in my opinion. After a certain point the wood loses its strength and the risk of further infestation remains as borer treatments wear off over years due to UV light exposure etc. Thanks for that - I was very inclined to do it but thought I'd ask communal opinion 'well just in case.'
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Post by Philconut on Aug 10, 2021 7:21:16 GMT 12
My case is missing the top lid for the cable tray so I will have to make a new one. Trouble is finding some of the same or a similar covering for it. I have actually cheated and removed the piece from the bottom and will use that but I would be interested in what you are going to do Peter. In its place, I have painted the bottom black.
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peter
Tinkerer
Retired, collector of vintage radios and test equipment for restoration and repair.
Posts: 97
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Post by peter on Aug 23, 2021 5:42:18 GMT 12
My case is missing the top lid for the cable tray so I will have to make a new one. Trouble is finding some of the same or a similar covering for it. I have actually cheated and removed the piece from the bottom and will use that but I would be interested in what you are going to do Peter. In its place, I have painted the bottom black. Well mine is a case of when I get a 'round tuit' - once I've acquired one of those I'll be laughing (either funny ha ha or funny peculiar - not sure which). At the moment the tester is carefully sealed up in plastic (to stop the woodworm getting out) and inside a plastic box inside a shed but it was one of the umpteen projects I've been eyeing over this lockdown. Trouble is I have so many it's getting rediculous - from simple rust removal and repaint (no electrical problems), to recap, to major investigations I seem to have put a lot of things aside 'for another day' as we tend to do. Was just recently telling Steve here how I went out to the shed to investigate a defective transformer and ended up pulling my Ultimate 70's shed radio to bits to see why it was not working - still in bits on my bench out there a week or so later
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Post by Philconut on Aug 23, 2021 8:51:37 GMT 12
Oh well, I suspect that you are not alone in that! I've certainly got several "in the wings". As a lockdown project I have started on a very, very sad HMV/RCA R4 Superette. It has an attractive cathedral cabinet in not bad order but the chassis is another story. It's interesting to see how these different sets are designed. This one has all the condensers in one large can, the driver & output transformers in another & all the resistors on a large tag board. It makes for a lot of wiring.
Cheers.
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Post by DHockey on Aug 26, 2021 20:22:45 GMT 12
My VCT is now completed. I have even had it working from 6 volts using the vibrator. However, I decided that a better use of the 6 volt vibrator winding on the transformer would be to power the ohms function via a 5 volt regulator and dispense with using a battery for this. The vibrator plugged into a UX-4 socket on the top of the transformer. I constructed a simple regulated 5 volt circuit using a LM309 on a piece of Veroboard mounted inside an old UX-4 valve base, connected the battery leads from the ohms range to the output and plugged it into the vibrator socket. 5 volts is a little higher than the 4.5v battery used originally, but in practice it makes no difference. Now I don’t have to think about flat batteries in the unit and the danger of leaking batteries is removed. The mod is also easily reversible, but I don’t think I’ll ever need to use the VCT away from the mains!
I also ended up having to replace the 30 ohm rheostat that serves as the range control for the valve tester. The resistance wire in the rheostat was making poor contact with the solder lugs(it was only wrapped around) The wire and the lugs were tarnished and would not take solder well even after cleaning. On measuring I found the rheostat to be 22ohms. Fortunately I had a 25 ohm rheostat that ended up being a suitable replacement, the resistance tracked spot on with the markings on the front panel.
Regarding the case, the latch, handle and hinges were all removed and cleaned up. As mentioned earlier I made up a new power cord compartment with some thin craft ply which was stained black to match the rest of the case The Rexine covering of the case was cleaned with Swarfega and was then polished up with black shoe polish.
Finally I made up some test leads and a top cap lead for the valve tester. I have been playing around with the VCT over the last couple of evenings and I'm quite happy with how it has turned out. It has some very useful functions and the valve tester is easy to set up and use compared to more complex testers, yes I know its only an emission tester, but for most radio work, shorts and emission will tell you all you need to know about a valve. I'm thinking that I will probably end up using the VCT quite a bit. I may even set myself a challenge of repairing a radio using the VCT and a vintage signal generator as my only test equipment.
John, I'm looking forwards to seeing your VCT when it is done. I hope you get the paint issue resolved!
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Post by DHockey on Aug 26, 2021 20:23:56 GMT 12
One more photo of the case closed up.
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Post by Philconut on Aug 26, 2021 21:02:37 GMT 12
An excellent result. The vibrator hasn't been fitted to my unit but the transformer winding is there. What a good idea to use it for the ohms range supply. I will stick with the batteries at the moment. Would you post a close-up of the vibrator socket & mounting please. I have made a new lid for the top compartment and covered it with the Rexine from the bottom. - totally successful. I'm now stuck with the front panel away being painted by one of our members and the hinges etc being plated. I will check the Range pot to see if it suffers from the same malady as yours. - I expect it will.
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Post by DHockey on Aug 26, 2021 21:26:32 GMT 12
Here you go, let me know if you want other angles.
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Post by Philconut on Aug 27, 2021 9:01:17 GMT 12
Many thanks. Now that I see how it's done it is quite obvious. I may install a similar socket.
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Post by Philconut on Aug 30, 2021 17:09:11 GMT 12
It's been a lackluster day here today so I decided I liked the idea of a regulator instead of batteries for the ohms ranges. As my VCT doesn't have a vibrator fitted, I had to make a bracket & install a 4 pin socket. My "supplies", I never throw anything out, provided all the necessary components and the picture is the final result. It works a treat & frees up the storage space. The metal cover is the top cap of a valve shield. As well, I have polished the case using black shoe polish. - amazing result! I'm still awaiting the front panel paint job.
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